Low occurrence of antibiotic resistance in Escherichia coli and staphylococci isolated from blood cultures in two Norwegian hospitals in 1991-92 and 1995-96

The aim of this study was to investigate the antibiotic resistance rates of major bacterial pathogens causing bloodstream infections in two very diffe rent types of hospital in Norway. We examined all Escherichia coli and stap hylococci (330 isolates) causing bloodstream infections from one general co unty hospital and one specialist national cancer hospital during the period s 1991-92 and 1995-96. Minimal inhibitory concentrations (MICs) were determ ined using the E-test. E. coli and staphylococci constituted 46.7% of all i solates from bloodstream infections in the two hospitals. Overall, E. coli isolates were resistant to amoxicillin (21%), trimethoprim (21%), doxycycIi ne (20%) and trimethoprimsulphamethoxazole (17%), while Staphylococcus aure us strains were resistant to benzylpenicillin (66%). No methicillin-resista nt S. aureus was detected. Coagulase-negative staphylococci were often mult iresistant, but remained fully sensitive to vancomycin. For a few antibioti cs, significantly more resistance was found in the specialist hospital. In our material we found no significant increase in resistance between 1991-92 and 1995-96. In conclusion, antimicrobial resistance still remains low in important bacterial pathogens causing bloodstream infections in Norway.